The present invention is drawn to heating units in general and, in particular, to a new and useful balancing air device for a heating unit which supplies outside air to the combustion chamber of the heating unit when it is operating and which includes a separate return line for providing the outside air directly to a chimney stack connected to the heating unit for satisfying a draft therein when the heating unit is not operating to prevent the loss of heat from the heating unit by the passage of air therethrough.
Various devices are known for improving the efficiency of heating units, in particular home heating units, in the interest of conservation of energy. Such devices include heat reclaimers connected to the exhaust flues of furnaces to withdraw excess heat from the waste gases before the heat is lost up the chimney.
The suggestion has been made that outside air should be used as combustion air for heating units. This special supply of outside air replaces the use of ambient air around the furance. See "Popular Science" article "Outside Venting" by Evan Powell, October, 1973.
In view of the recent drastic increase in energy costs, it has become a general practice to increase the insulation of dwellings and reduce drafts and other air leakages around the windows and doors. Since heating units are usually provided with combustion air from within the dwelling, such leaks and drafts were relied upon to supply sufficient quantities of combustion air. In extreme cases, a dangerous situation may arise whereby insufficient amounts of oxygen are supplied to the furnace so that the fuel, whether gas or oil, is burned incompletely, causing incomplete, inefficient combustion and producing such dangerous by-products as carbon monoxide and the like. The provision of a special air line for supplying outside air to a furnace or boiler has been found to avoid these difficulties and also to reduce heat losses within the dwelling by permitting the effective sealing of all leaks and drafts.